: Despite widespread knowledge of HIV infection risk associated with certain sexual behaviors, current incident HIV infection rate in homosexually active younger men and especially men from African-American ethnic/racial backgrounds, indicate continuing occurrence of higher risk behaviors within these subpopulations. Uninfected men from these higher risk segments of the homosexually active male population will likely serve as one of the important source populations in the development of a preventive HIV vaccine and, should such successful development occur, a target population for vaccination campaign. trials. The results of the proposed study will provide important behavioral data that will facilitate both possible vaccine trial studies and overall behavioral prevention programs directed at high risk young African-American men who have sex with men. The proposed survey of homosexually active African-American (n=300) and White men (n-100), between the ages of 18-29 years, all HIV uninfected and so potentially eligible for preventive HIV vaccines, will develop estimates of vaccine trials-related attitudes and behaviors. The study will also examine sexual behavior patterns and their determinants and barriers to effective participation in future vaccine trials. Findings from this study will provide critically needed data concerning high risk sexual behavior pattern's in various subpopulations of young African-American gay men, identify possible difficulties in recruiting these men into vaccine trials, and assist in providing basic behavioral data relevant to the overall development of HIV-related health interventions (e.g., culturally-specific behavioral counseling) and prevention campaigns with young, homosexually active African-American men. Regardless of the speed by which a possible vaccine is developed, the overall continuing high rates of incident HIV infections among young African American men who have sex with men makes them a critically important target population for the development of efficacious, preventive behavioral interventions. One method for accomplishing the development of efficacious prevention efforts in this high risk population of young African-American gay men is through better determination of the meaning of behavior from the ethnic, cultural perspective of these men as well as an understanding of the unique subcultures present that serve to influence and trigger risk behavior hammering effective risk reduction efforts. The increased sample size of Black men will facilitate - identification of subpopulations and significant contextual factors which influence risk behaviors.